John Wood Envirosense Power Direct Vent (May 2010 or later) - Manuel (Page 15)

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Minimum clearances between the water heater and combustible
construction are 0 inch at the sides and rear, 5.5” (14.0 cm) from
the front and 18” (45.7 cm) from the top. (Standard clearance.) If
clearances stated on the heater differ from standard clearances, install
water heater according to clearances stated on the heater.
Adequate clearance 30” (76 cm) for servicing this water heater should
be considered before installation, such as changing the anode rods,
control system components and gas control valve.
A minimum clearance of 5.5” (14.0 cm) must be allowed for access to
replaceable and/or serviceable parts such as the thermostats, drain valve,
condensate drain, temperature-pressure relief valve, clean out opening,
and the vent connection (exhaust elbow).
When installing the heater, consideration must be given to proper
location. Location selected should be as close to the wall as practicable
and as centralized with the water piping system as possible.
Figure 3: CLEARANCES
INSULATION BLANKETS
Insulation blankets are available to the general public for external use
on gas water heaters but are not necessary with these products. The
purpose of an insulation blanket is to reduce the standby heat loss
encountered with storage tank heaters. Your water heater meets or
exceeds the Energy Policy Act standards with respect to insulation and
standby loss requirements, making an insulation blanket unnecessary.
Should you choose to apply an insulation blanket to this heater, you
should follow these instructions (For identification of components
mentioned below, see “Figure 1B: 50 GALLON UNIT” & “Figure 1C:
75 GALLON UNIT”. Failure to follow these instructions can restrict
the air flow required for proper combustion, potentially resulting in
fire, asphyxiation, serious personal injury or death.
• Do not apply insulation to the top of the water heater, as this will
interfere with safe operation of the blower assembly.
• Do not cover the control system LCD on top of the water heater.
• Do not cover the outer door, thermostat or temperature & pressure
relief valve.
• Do not cover the instruction manual. Keep it on the side of the
water heater or nearby for future reference.
• Do obtain new warning and instruction labels from the manufacturer
for placement on the blanket directly over the existing labels.
• Do inspect the insulation blanket frequently to make certain it does
not sag, thereby obstructing combustion air flow.
COMBUSTION AIR AND VENTILATION
A gas water heater cannot operate properly without the correct
amount of air for combustion. Do not install in a confined area such
as a closet, unless you provide air as shown in the Facts to Consider
About Location section. Never obstruct the flow of ventilation air. If
you have any doubts or questions at all, call your gas supplier. Failure
to provide the proper amount of combustion air can result in a fire or
explosion and cause death, serious bodily injury, or property damage.
Figure 4: COMBUSTION AIR AND VENTILATION
If this water heater will be used in beauty shops, barber shops,
cleaning establishments, or self-service laundries with dry cleaning
equipment, it is imperative that the water heater(s) be installed
direct vent so that all air for combustion and ventilation is taken
from outdoors.
Propellants of aerosol sprays and volatile compounds, (cleaners,
chlorine based chemicals, refrigerants, etc.) in addition to being
highly flammable in many cases, will also react to form corrosive
hydrochloric acid when exposed to the combustion products of
the water heater. The results can be hazardous, and also cause
product failure.